This application is related to U.S. Pat. No. 4,476,788 and the teachings of that application are herein incorporated by this reference.
1. Field of the Invention
This invention relates to an improved fluid medium heated outlet valve centrally located at the bottom of a railway tank car.
2. Description of the Prior Art
Heated outlet valves for facilitating the emptying or removal of the cargo or lading from railway tank cars are old and well-known. Such valves, which may be of either the plug or the ball or the wafer type are typically bolted, or otherwise sealingly engaged flush with the inner lower surface of the bottom of the tank of the car. Typically a steam jacket surrounds the valve at the exterior of the car below the exterior surface of the tank. Consequently such valves depend, or the steam jackets of such valves depend or suspend, a substantial distance beneath the lower exterior surface of the car and are subject to damage from mechanical engagement of objects passing beneath the car. Also, the exterior of the steam jacket is surrounded by air and inefficiently radiates heat into that surrounding air rather than using that heat to raise the temperature and consequently lower the viscosity of the lading immediately above and adjacent the valve.